1. Field of the Invention
The present invention relates to a process for producing alkoxylated esters and, more particularly, to a process for producing such esters having a narrow homolog distribution of the alkoxylated ester.
2. Description of the Prior Art
Alkoxylated esters, e.g. alkoxylated esters of fatty acids, are well known and find use in surfactant and other applications. Such esters can be prepared by various techniques well known in the art. For example, German reference DE 3914131 describes the alkoxylation of fatty acid esters using calcined hydrotalcites as catalysts. It is also well known to prepare such alkoxylated fatty acid esters using sodium hydroxide/alcohol and sodium methoxide catalysts. The use of catalysts such as sodium hydroxide and sodium methoxide results in the production of alkoxylated esters having a broad homolog distribution of the alkoxylated product. Additionally, the reaction times using these catalysts is slow and conversions are low. Although the use of hydrotalcite, as discussed in the above referenced German patent publication, is claimed to produce the alkoxylated fatty acid ester in high yield with a narrow homolog distribution, the distribution of the end product cannot be considered truly "peaked", i.e. with the desired narrow distribution of homologs.
U.S. Pat. No. 4,820,673 discloses a calcium based catalyst for use in the alkoxylation of organic compounds having at least one active hydrogen to provide end products having a narrow distribution of the alkoxylation species.
U.S. Pat. No. 4,835,321 discloses another type of calcium based catalyst for the alkoxylation of alcohols to provide alkoxylated alcohols having a narrow distribution of the alkoxylation species.